Investigation of posible cardio-pulmonary abnormalities responsible for the sudden infant death syndrome (SIDS) is continuing. Wuantitative, histologic studies of the central nervous system are to be completed, particularly those that control respiration. 240 fetal, intrapartum and neonatal clinical items in the collaborative study of the NINDS are to be compared in SIDS and control cases in an attempt to develop a high risk profile for SIDS. Quantitative studies of the heart are to be completed comparing SIDS victims with controls.